1. Field of the Invention
The present invention relates to a shaped resin article. More particularly, the present invention is concerned with a shaped resin article comprising: a polyamide (A) comprising at least two different polyamide components, a polyphenylene ether (B), and a specific partially hydrogenated block copolymer (C), wherein polyamide (A) is present as a continuous phase in which polyphenylene ether (B) is dispersed to form a dispersed phase, and partially hydrogenated block copolymer (C) is present in at least one phase selected from the group consisting of the continuous phase of polyamide (A) and the dispersed phase of polyphenylene ether (B), wherein polyamide (A) is exposed on the surface of the shaped resin article so that the total area of the polyamide (A) exposed on the surface of the shaped resin article is at least 80%, based on the surface area of the shaped resin article. The shaped resin article of the present invention is advantageous not only in that the shaped resin article has excellent matte surface, but also in that the shaped resin article has excellent strength of adhesion to a coating formed on the shaped resin article (which strength of adhesion is hereinafter, referred to simply as “coating adhesion strength”), and such a coating formed on the shaped resin article has excellent sharpness of an image reflected therein (i.e., the coating has excellent luster). The present invention is also concerned with a conductive resin composition comprising: a polyamide (A), a polyphenylene ether (B), a specific block copolymer (C), a conductive carbonaceous material (D), and wollastonite particles (E). By the use of the conductive resin composition of the present invention, it becomes possible to produce a shaped article which is advantageous not only in that the shaped article has excellent matte surface, but also in that the shaped article has excellent coating adhesion strength, and a coating formed on the shaped article has excellent sharpness of an image reflected therein. Further, the produced shaped article has a satisfactorily low coefficient of linear expansion, which is especially advantageous in the field of large shaped articles, such as an automobile fender and an automobile back door. The shaped resin article of the present invention and the shaped article produced from the conductive resin composition of the present invention can be advantageously used in a wide variety of fields, e.g., not only in a field of exterior parts for automobiles, but also in the fields of electric and electronic parts, parts of office automation machines, mechanical parts, and electric and interior parts of motorcycles and automobiles.
2. Prior Art
Polyphenylene ethers not only have excellent mechanical properties, excellent electrical properties (such as dielectric constant and dielectric dissipation factor) and excellent heat resistance, but also have excellent dimensional stability. Therefore, polyphenylene ethers have been used in a wide variety of fields. However, the moldability of a polyphenylene ether is poor. For improving the moldability of a polyphenylene ether, Examined Japanese Patent Publication No. Sho 45-997 discloses a technique in which a polyamide is added to a polyphenylene ether, to thereby obtain a polyamide-polyphenylene ether alloy. Further various new techniques relating to polyamide-polyether alloys are proposed in, for example, U.S. Pat. Nos. 4,315,086, 4,732,938 and 4,659,760. Nowadays, polyamide-polyether alloys are used in a very wide variety of fields, such as exterior parts for automobiles.
Many of exterior parts of automobiles are usually coated. Therefore, in the choice of a material for exterior parts of automobiles, the strength of adhesion of a material to a coating (which strength of adhesion is hereinafter, referred to simply as “coating adhesion strength”) is an important factor.
Conventionally, various techniques have been proposed for imparting coating adhesion strength to a polyamide-polyphenylene ether alloy. For example, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 8-109324 (corresponding to U.S. Pat. No. 5,554,693) discloses a technique in which a specific terpene phenol resin is added to a polyamide-polyphenylene ether alloy so as to improve the coating adhesion strength of the alloy. Further, Unexamined Japanese Patent Application Laid-Open Specification No. Hei 3-143571 discloses a technique in which a shaped resin article is treated with a surfactant, thereby improving the coating adhesion strength of the shaped resin article without precoating of the shaped article with a primer.
However, each of the above-mentioned techniques poses a problem in that an additive is used to improve the coating adhesion strength of the alloy, thereby causing disadvantages in that the heat resistance of the alloy gets lowered, and in that the coated shaped particle of the alloy absorbs moisture. Therefore, there has been a market demand for a technique for improving the coatability of a shaped resin article without the use of an additive.
Further, as one of the properties which are required of large shaped articles (such as an automobile fender and an automobile back door), there can be mentioned a low coefficient of linear expansion. In an automobile, there is provided a gap between an automobile fender and a door, which gap is necessary for opening and closing the door. When an automobile fender is produced from a material having a high coefficient of linear expansion, a disadvantage is caused in that the size of the above-mentioned gap changes depending on the ambient temperature. Therefore, it has been desired to improve the coefficient of linear expansion of a material used for producing the above-mentioned large shaped articles.
In general, the coefficient of linear expansion of a material can be improved by adding an organic or inorganic filler. However, when an organic or inorganic filler is added to a material, a shaped article produced from the material is disadvantageous not only in that the organic or inorganic filler is likely to be biasedly present near the surface of the shaped article, but also in that the coating adhesion strength is lowered, and a coating formed on the shaped article has poor luster. Therefore, it has been desired to improve simultaneously the coefficient of linear expansion and coating adhesion strength of a shaped article, and the luster of a coating formed on the shaped article.